The present invention relates to a projector lamp unit, and more particularly, to a projector lamp unit for which a countermeasure is taken to enhance safety by means of preventing thermal deterioration of a resin-covering wire pulled out of the inside of a lamp case housing a lamp.
FIG. 8 descriptively shows the basic configuration of a projector. In this projector, a fan 400 used for generating a current of air and a lens unit 500 for projection purpose as well as a lamp unit 100, an engine 200, and a power unit 300 are incorporated in a flat box-shaped housing. An image projected by the lens unit 500 is displayed on a screen located ahead of the lens unit while the lamp unit 100 is taken as a light source. In the projector of this type, the lamp unit 100 is one of the heat-producing sources that generate the highest heat.
Incidentally, the lamp unit 100 has a lamp case made from aluminum and a lamp accommodated in the lamp case. A resin-covering feeding wire led from the lamp is pulled out of the inside of the lamp case. A coating forming a resin sheath layer of the resin-coating wire is provided with heat resistance of about 200° C. or thereabouts. In contrast, the lamp case is expected to be heated up to 150° C. or more as a result of operation of the lamp unit 100.
In such a projector, even when the lamp case is heated up to 150° C. or more, the coating of the resin-covering wire of the lamp unit 100 is provided with heat resistance of about 200° C. Hence, the coating is considered to be impervious to thermal deterioration. In reality, when the coating of the resin-covering wire remains in contact with a highly-heated lamp case at a location where the wire is inserted into the lamp case, there may arise a case where the coating melts. Provided that the coating melts to thus make an internal core wire bare, a high-voltage current of the resin-coating wire is connected to a ground level of the lamp case, which may break electronic components, such as a digital micromirror device (DMD). Moreover, the hot air circulating through the inside of the lamp case by means of convection is also heated up to about 200° C. Therefore, the air continually contacts the coating of the resin-covering wire to thus thermally deteriorate the coating, or the coating is deteriorated upon exposure to UV radiation. Moreover, minimizing emission of the hot air in the lamp case to the outside by way of the location where the resin-coating wire is inserted into the lamp case is desirable. If emission of such a hot air is not sufficiently avoided, the internal temperature of the housing will be excessively increased, which may create various inconveniences.
Meanwhile, there is a related lamp unit where an end of the lead wire which is led from the lamp and routed through the internal space of the house, is connected to a terminal attached to the house housing a lamp with a mirror (see, e.g., JP-A-2002-75014).
In a display element of a large-size display device, a lead wire withdrawn from the lamp is made short, and the end of the lead wire is connected to a connector section via a conductive pattern (see, e.g., JP-A-8-203421). Moreover, there are a light source (see, e.g., JP-A-2002-222601) where a cylindrical metal tube, by way of which a power-feeding line drawn from a discharge lamp is to be inserted, is provided on a curved surface of a concave reflection mirror provided around the discharge lamp, and a short arc metal halide lamp (see, e.g., Japanese Utility Model Registration No. 3004793) where a wire led from a short arc metal halide lamp is fixed to a metallic terminal attached to a reflection mirror.
However, JP-A-2002-75014, JP-A-8-203421, JP-A-2002-222601 and Japanese Utility Model Registration No. 3004793 do not suggest any countermeasures against thermal deterioration of a coating of a lead wire, a power-feeding line, or a wire corresponding to the resin-covering wire described at the outset.